1. Technical Field
The present invention generally relates to a method of making high-purity fine particles of reactive metals and a manufacturing vessel therefor, and relates more particularly to a method of making high-purity fine particles of reactive metals of IIa, IIIa, IVa and IVb families in the periodic table and a manufacturing vessel therefor, which reactive metals are apt to form hydroxides such as Sr, Ba and Y, that are the elements basic to the making of superconducting materials, and Hf, that is valued for its high hardness and thermal resistance.
2. Background Art
Presently, the need for manufacturing high-purity fine particles of reactive metals, especially those which are liable to form hydroxides, i.e., metals of IIa, IIIa, IVa and IVb families in the periodical table, is mounting because of demands from the advanced materials sector, such as superconducting materials. Here, one technical problem exists in that, since these metals are apt to absorb and retain undesired gases and to become surface oxidized, or in the case of the IIa metals, in particular, to form hydroxide by actively reacting with moisture, as they are pulverized and so increase their surface area, attainment of necessary high purity is very difficult. In fact, it can be said that no satisfactory method has been made available up to the present.
A currently popular method of making superconducting materials, which are compounded oxides of Sr, Ba, Y, La, Cu, and other elements, is to use salts or oxides of these metals as the raw materials. For making Hf materials of high hardness and thermal resistance, on the other hand, carbide of metallic Hf obtained in hydrogen-reducing Hf salts is used.
The problems in these methods are then that, since the raw materials are usually metallic compounds, the reaction system is necessarily more complex than the case of using high-purity fine particles, resulting in lowered purity, hence degradation of desired properties, of the product. When salts are used, in particular, elements and groups that are not of the necessary constituents for the final product are apt to be liberated through dissociation during processing, leaving voids and other crystalline defects behind.
That the reaction system is complex means, moreover, that manufacturing has to be conducted in a multitude of steps, calling for large investment in equipment and high manufacturing costs in mass production.
These difficulties can be eliminated if and when these reactive metals are provided in a finely particulated form, with high purity, and in large quantities. However, as stated earlier, neither a satisfactory method nor an apparatus for production is available today.